Display technology experienced rapid development over the past several years. For example, in terms of Thin Film Transistor (TFT) technologies, amorphous Silicon (a-Si) TFTs are gradually replaced with Low Temperature Poly Silicon (LTPS) TFTs, Metal Induced Lateral Crystallization (MILC) TFTs and Oxide TFTs. As for light emitting technologies, the previously available Liquid Crystal Displays (LCDs), Plasma Display Panels (PDPs) are replaced with Organic Light Emitting Diodes (OLEDs), Active Matrix Organic Light Emitting Diodes (AMOLEDs) and the like. As a new generation of displays, organic light emitting displays have the advantages of self-luminous, fast response, wide viewing angle and applicable to flexible displays, transparent displays and 3D displays, in comparison with LCDs. However, whether the display device is a LCD or an organic light emitting display, a switch device, such as a TFT, is required to control each pixel in the display, such that each pixel can be control independently through a drive circuit while not causing crosstalk to other pixels.
Oxide TFTs that use an oxide semiconductor as the active layer have the advantages of high mobility, high ON-state current, better switch characteristics. Therefore, oxide TFTs are widely used in applications requiring fast response and large current, such as high frequency, high resolution, and large dimension displays and OLED displays.
However, conventional methods for fabricating oxide TFTs generally comprise six patterning processes respectively for forming a gate line and a gate electrode, a gate insulation layer, an active layer, an etch stop layer, a source/drain electrode, a passivation layer and via holes. Six exposure processes by using a mask will render the performance of the TFTs instable, the fabrication cycle long, and the fabrication cost high.